By counting the same set in two ways, prove the following identity:
n ∑ k = 0 ( k m ) ( n k ) = ( n m ) 2 n − m . ∑k=0n(km)(nk)=(nm)2n−m. notes: for there is no meaning to the word "towers" other than what is given: ∅ ⊆ a ⊆ b ⊆ { 1 , 2 , … , n } .

answer: 94

step-by-step explanation: 79+91+92+94+94 = 450 divided by 5 (since there are 5 number that are being added) = 90

x² + 3x + 7 = 0       [ax² + bx + c]

a = 1

b = 3

c = 7

quadratic formula:

    (+/- is this ±)

plug in the numbers into the variables

your answer is a